Gasoline service stations normally have underground storage tanks from which the fuel is pumped to dispensing units. A typical installation makes use of a submersible electric pump in the storage tank which operates to pump gasoline or another fuel to a distribution head located above the tank. From the distribution head, the fuel is supplied to the dispensers.
The flow path for the fuel includes a vertical column pipe which extends from the pump to the distribution head. In order to supply electrical power to the pump, the distribution head has electrical connections which are suitably connected with a power source. A conduit extending through the column pipe contains lead wires which supply power to the pump from the electrical connections of the distribution head.
Industry regulations and general safety considerations require that the electrical system meet prescribed standards. It is critical that the electrical system be completely isolated from the fuel in order to prevent fires or explosions that could result from an electrical spark or other electrical problem. It is also necessary to prevent undue leakage of fuel from the column pipe to the surrounding environment. Any field assembly of the components that is necessary must be carried out in a manner to assure compliance with all applicable safety and environmental requirements.
The storage tanks vary in capacity and also vary as to the depth at which they are buried. Consequently, the length of the column pipe assembly can vary considerably between different installations. For this reason, there is a need for a column pipe assembly that can be adjusted in length while maintaining compliance with applicable safety and environmental regulations.